Page 106 - DMGT209_QUANTITATIVE_TECHNIQUES_II

Unit 6: Research Design

two advertisements. Assume that the respondent exposed to ‘A’ are the dominant users of Notes
the product. Now, suppose 50% of those who saw Advertisement A bought the product
and only 10% of those who saw Advertisement B bought the product. From the above, one
should not conclude that advertisement ‘A’ is more effective than advertisement ‘B’. The
main difference may be due to food preference habits between the groups; even in this
case, the internal validity might suffer but to a lesser degree.
 Experimental Mortality: Some members may leave the original group and some new
members may join the old group. This is because some members might migrate to another
geographical area. This change in composition of the members will alter the composition
of the group itself.

Example: Assume that a vacuum cleaner manufacturer wants to introduce a new version.
He interviews hundred respondents who are currently using the older version. Let us assume
that, these 100 respondents have rated the existing vacuum cleaner on a 10 point scale (1 for
lowest and 10 for highest). Let the mean rating of the respondents be 7.

Now the newer version is demonstrated to the same hundred respondents and the equipment is
left with them for two months. At the end of two months, only 80 participants respond, since the
remaining 20 refused to answer. Now the mean score of 80 respondents is 8 on the same 10 point
scale. From this, can we conclude that the new vacuum cleaner is better?
The answer to the above question depends on the composition of 20 respondents who dropped
out. Suppose the 20 respondents who dropped out displayed negative reaction to the product,
then the mean score would not have been 8. It would have been even lower than 7. The difference
in mean rating does not give the true picture. It does not indicate that the new product is better
than the old one.
One might wonder, why not we leave the 20 respondents from the original group and calculate
the mean rating of the remaining 80 and compare the two? But this method will also not solve
the mortality effect. Mortality effect will occur in an experiment, irrespective of whether human
beings are involved or not.

Task You are the manager of product planning and marketing research for a home
appliance stores. Your company is considering a proposal to manufacture and market an
emergency lamp in which segment the company currently does not have any product.
You have assigned this project to one of your subordinates.
(a) Is this an exploratory, descriptive, or a causal study?
(b) What data would be useful for deciding whether to develop an emergency lamp or
not?
(c) How will you design a study to obtain the needed data?

Self Assessment

Fill in the blanks:
13. ………………Research is also known as causal research.
14. Extraneous Variables are also known as …………..variables.

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